Antenna switch scheduling

ABSTRACT

Methods, systems, and devices for wireless communication are described. A multi-antenna user equipment (UE) may communicate with a base station using a first antenna, determine to switch from the first antenna to a second antenna for communicating with the base station, determine a silence window in which communication with the base station is suspended, schedule the switch from the first antenna to the second antenna to occur during the silence window, and switch from the first antenna to the second antenna during the silence window.

CLAIM OF PRIORITY UNDER 35 U.S.C. § 120

The present application for patent is a Continuation of patentapplication Ser. No. 16/557,783 entitled “ANTENNA SWITCH SCHEDULING”filed Aug. 30, 2019, pending, and assigned to the assignee hereof andhereby expressly incorporated by reference herein.

BACKGROUND Field of the Disclosure

The following relates generally to wireless communication, and morespecifically to antenna switch scheduling in a multi-antenna userequipment (UE).

Description of Related Art

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., time, frequency, and power). Examples of suchmultiple-access systems include fourth generation (4G) systems such asE-UTRA, or Long Term Evolution (LTE) or LTE-Advanced (LTE-A), systems,and fifth generation (5G) systems which may be referred to as New Radio(NR) systems. These systems may employ technologies such as codedivision multiple access (CDMA), time division multiple access (TDMA),frequency division multiple access (FDMA), orthogonal frequency divisionmultiple access (OFDMA), or discrete Fourier transform-spread-OFDM(DFT-S-OFDM). A wireless multiple-access communications system mayinclude a number of base stations or network access nodes, eachsimultaneously supporting communication for multiple communicationdevices, which may be otherwise known as user equipment (UE).

Generally, base stations and UEs communicate via transmissions onforward and reverse links. A forward link (or downlink) refers to thecommunication link from a base station to a UE, and the reverse link (oruplink) refers to the communication link from the UE to the basestation. The forward and/or reverse links may be established viasingle-in-single-out (SISO), multiple-in-single-out (MISO), or amultiple-in-multiple-out (MIMO) system. In devices utilizing multipleantennas, algorithms may exist for switching between antennas to achievea desired performance (e.g., to switch from using a certain antenna thatmay be blocked by how a device is held). Moreover, some UEs may beconfigured to communicate with base stations using multiple radio accesstechnologies, such as in an E-UTRA New Radio-Dual Connectivity (EN-DC)mode.

SUMMARY

The described techniques relate to improved methods, systems, devices,or apparatuses that support antenna switch scheduling in a multi-antennauser equipment (UE).

A method of wireless communication in a multi-antenna UE is described.The method may include communicating with a base station using a firstantenna, determining to switch from the first antenna to a secondantenna for communicating with the base station, determining a silencewindow in which communication with the base station is suspended,scheduling the switch from the first antenna to the second antenna tooccur during the silence window, and switching from the first antenna tothe second antenna during the silence window.

A multi-antenna UE is described. The UE may include a first antenna, asecond antenna, a processor, memory coupled to the processor, andinstructions stored in the memory. The instructions may be executable bythe processor to cause the UE to communicate with a base station usingthe first antenna, determine to switch from the first antenna to thesecond antenna for communicating with the base station, determine asilence window in which communication with the base station issuspended, schedule the switch from the first antenna to the secondantenna to occur during the silence window, and switch from the firstantenna to the second antenna during the silence window.

An apparatus for wireless communication is described. The apparatus mayinclude means for communicating with a base station using a firstantenna, means for determining to switch from the first antenna to asecond antenna for communicating with the base station, means fordetermining a silence window in which communication with the basestation is suspended, means for scheduling the switch from the firstantenna to the second antenna to occur during the silence window, andmeans for switching from the first antenna to the second antenna duringthe silence window.

A non-transitory computer readable medium storing code for wirelesscommunication is described. The code may include instructions executableby a processor to communicate with a base station using a first antenna,determine to switch from the first antenna to a second antenna forcommunicating with the base station, determine a silence window in whichcommunication with the base station is suspended, schedule the switchfrom the first antenna to the second antenna to occur during the silencewindow, and switch from the first antenna to the second antenna duringthe silence window.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a system for wireless communicationthat supports antenna switch scheduling in a multi-antenna userequipment (UE) in accordance with aspects of the present disclosure.

FIG. 2 is a block diagram of portions of a multi-antenna UE thatsupports antenna switch scheduling in accordance with aspects of thepresent disclosure.

FIG. 3 is a block diagram of portions of a multi-antenna UE thatsupports multiple-input-multiple-output (MIMO) antenna switch schedulingin accordance with aspects of the present disclosure.

FIGS. 4-8 are timeline diagrams depicting UE operations in antennaswitch scheduling in accordance with aspects of the present disclosure.

FIG. 9 illustrates a block diagram of a device that supports antennaswitch scheduling in accordance with aspects of the present disclosure.

FIG. 10 illustrates a block diagram of a system including amulti-antenna UE that supports antenna switch scheduling in accordancewith aspects of the present disclosure.

FIGS. 11 and 12 illustrate methods for antenna switch scheduling in amulti-antenna UE in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure provide techniques for schedulingantenna switching in a multi-antenna user equipment (UE). In one aspect,a UE may determine to switch from a first antenna to a second antenna incommunicating with a base station. Switching from one antenna to anotherantenna may involve suspending communication to avoid damagingcomponents (e.g., front end components such as a power amplifier) of theUE and/or to change settings (e.g., antenna switched diversity (ASDIV)configurations) of components. Suspending communication during aconnection with a base station may result in communication delays and/oroutages. In an aspect, the UE may determine whether an upcoming silencewindow is available and may schedule the antenna switch to occur duringthe silence window. In some aspects, scheduling an antenna switch mayreduce outages or loss of connection due to transmission and/orreception suspension or blanking.

Aspects of the disclosure are initially described in the context of awireless communications system. Aspects of the disclosure are furtherillustrated by and described with reference to apparatus diagrams,timeline diagrams, system diagrams, and flowcharts that relate toantenna switch scheduling in a multi-antenna UE.

FIG. 1 illustrates an example of a wireless communications system 100that supports antenna switch scheduling in a multi-antenna UE inaccordance with various aspects of the present disclosure. The wirelesscommunications system 100 includes base stations 105, UEs 115, and acore network 130. In some aspects, the wireless communications system100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A)network, or a New Radio (NR) network. In some cases, wirelesscommunications system 100 may support enhanced broadband communications,ultra-reliable (e.g., mission critical) communications, low latencycommunications, or communications with low-cost and low-complexitydevices.

Base stations 105 may wirelessly communicate with UEs 115 via one ormore base station antennas. Base stations 105 described herein mayinclude or may be referred to by those skilled in the art as a basetransceiver station, a radio base station, an access point, a radiotransceiver, a NodeB, an eNodeB (eNB), a next-generation Node B orgiga-nodeB (either of which may be referred to as a gNB), a Home NodeB,a Home eNodeB, or some other suitable terminology. Wirelesscommunications system 100 may include base stations 105 of differenttypes (e.g., macro or small cell base stations). The UEs 115 describedherein may be able to communicate with various types of base stations105 and network equipment including macro eNBs, small cell eNBs, gNBs,relay base stations, and the like.

Each base station 105 may be associated with a particular geographiccoverage area 110 in which communications with various UEs 115 issupported. Each base station 105 may provide communication coverage fora respective geographic coverage area 110 via communication links 125,and communication links 125 between a base station 105 and a UE 115 mayutilize one or more carriers. Communication links 125 shown in wirelesscommunications system 100 may include uplink transmissions from a UE 115to a base station 105, or downlink transmissions, from a base station105 to a UE 115. Downlink transmissions may also be called forward linktransmissions while uplink transmissions may also be called reverse linktransmissions.

The geographic coverage area 110 for a base station 105 may be dividedinto sectors making up only a portion of the geographic coverage area110, and each sector may be associated with a cell. In some aspects,each base station 105 may provide communication coverage for a macrocell, a small cell, a hot spot, or other types of cells, or variouscombinations thereof. In some aspects, a base station 105 may be movableand therefore provide communication coverage for a moving geographiccoverage area 110. In some aspects, different geographic coverage areas110 associated with different technologies may overlap, and overlappinggeographic coverage areas 110 associated with different technologies maybe supported by the same base station 105 or by different base stations105. The wireless communications system 100 may include, for example, aheterogeneous LTE/LTE-A or NR network in which different types of basestations 105 provide coverage for various geographic coverage areas 110.

The term “cell” refers to a logical communication entity used forcommunication with a base station 105 (e.g., over a carrier), and may beassociated with an identifier for distinguishing neighboring cells(e.g., a physical cell identifier (PCID), a virtual cell identifier(VCID)) operating via the same or a different carrier. In some aspects,a carrier may support multiple cells, and different cells may beconfigured according to different protocol types (e.g., machine-typecommunication (MTC), narrowband Internet-of-Things (NB-IoT), enhancedmobile broadband (eMBB), or others) that may provide access fordifferent types of devices. In some cases, the term “cell” may refer toa portion of a geographic coverage area 110 (e.g., a sector) over whichthe logical entity operates.

UEs 115 may be dispersed throughout the wireless communications system100, and each UE 115 may be stationary or mobile. A UE 115 may also bereferred to as a mobile device, a wireless device, a remote device, ahandheld device, or a subscriber device, or some other suitableterminology, where the “device” may also be referred to as a unit, astation, a terminal, or a client. A UE 115 may also be a personalelectronic device such as a cellular phone, a personal digital assistant(PDA), a tablet computer, a laptop computer, or a personal computer. Insome aspects, a UE 115 may also refer to a wireless local loop (WLL)station, an Internet of Things (IoT) device, an Internet of Everything(IoE) device, or an MTC device, or the like, which may be implemented invarious articles such as appliances, vehicles, meters, or the like.

Some UEs 115, such as MTC or IoT devices, may be low cost or lowcomplexity devices, and may provide for automated communication betweenmachines (e.g., via Machine-to-Machine (M2M) communication). M2Mcommunication or MTC may refer to data communication technologies thatallow devices to communicate with one another or a base station 105without human intervention. In some aspects, M2M communication or MTCmay include communications from devices that integrate sensors or metersto measure or capture information and relay that information to acentral server or application program that can make use of theinformation or present the information to humans interacting with theprogram or application. Some UEs 115 may be designed to collectinformation or enable automated behavior of machines. Examples ofapplications for MTC devices include smart metering, inventorymonitoring, water level monitoring, equipment monitoring, healthcaremonitoring, wildlife monitoring, weather and geological eventmonitoring, fleet management and tracking, remote security sensing,physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reducepower consumption, such as half-duplex communications (e.g., a mode thatsupports one-way communication via transmission or reception, but nottransmission and reception simultaneously). In some aspects half-duplexcommunications may be performed at a reduced peak rate. Other powerconservation techniques for UEs 115 include entering a power saving“deep sleep” mode when not engaging in active communications, oroperating over a limited bandwidth (e.g., according to narrowbandcommunications). In some cases, UEs 115 may be designed to supportcritical functions (e.g., mission critical functions), and a wirelesscommunications system 100 may be configured to provide ultra-reliablecommunications for these functions.

In some cases, a UE 115 may also be able to communicate directly withother UEs 115 (e.g., using a peer-to-peer (P2P) or device-to-device(D2D) protocol). One or more of a group of UEs 115 utilizing D2Dcommunications may be within the geographic coverage area 110 of a basestation 105. Other UEs 115 in such a group may be outside the geographiccoverage area 110 of a base station 105, or be otherwise unable toreceive transmissions from a base station 105. In some cases, groups ofUEs 115 communicating via D2D communications may utilize a one-to-many(1:M) system in which each UE 115 transmits to every other UE 115 in thegroup. In some cases, a base station 105 facilitates the scheduling ofresources for D2D communications. In other cases, D2D communications arecarried out between UEs 115 without the involvement of a base station105.

Base stations 105 may communicate with the core network 130 and with oneanother. In some aspects, base stations 105 may interface with the corenetwork 130 through backhaul links 132 (e.g., via an S1 or otherinterface). Base stations 105 may communicate with one another overbackhaul links 134 (e.g., via an X2 or other interface) either directly(e.g., directly between base stations 105) or indirectly (e.g., via corenetwork 130).

The core network 130 may provide user authentication, accessauthorization, tracking, Internet Protocol (IP) connectivity, and otheraccess, routing, or mobility functions. The core network 130 may be anevolved packet core (EPC), which may include at least one mobilitymanagement entity (MME), at least one serving gateway (S-GW), and atleast one Packet Data Network (PDN) gateway (P-GW). The MME may managenon-access stratum (e.g., control plane) functions such as mobility,authentication, and bearer management for UEs 115 served by basestations 105 associated with the EPC. User IP packets may be transferredthrough the S-GW, which itself may be connected to the P-GW. The P-GWmay provide IP address allocation as well as other functions. The P-GWmay be connected to the network operators IP services. The operators IPservices may include access to the Internet, Intranet(s), an IPMultimedia Subsystem (IMS), or a Packet-Switched (PS) Streaming Service.

At least some of the network devices, such as a base station 105, mayinclude subcomponents such as an access network entity, which may be anexample of an access node controller (ANC). Each access network entitymay communicate with UEs 115 through a number of other access networktransmission entities, which may be referred to as a radio head, a smartradio head, or a transmission/reception point (TRP). In someconfigurations, various functions of each access network entity or basestation 105 may be distributed across various network devices (e.g.,radio heads and access network controllers) or consolidated into asingle network device (e.g., a base station 105).

Wireless communications system 100 may operate using one or morefrequency bands, typically in the range of 300 MHz to 300 GHz.Generally, the region from 300 MHz to 3 GHz is known as the ultra-highfrequency (UHF) region or decimeter band, since the wavelengths rangefrom approximately one decimeter to one meter in length. UHF waves maybe blocked or redirected by buildings and environmental features.However, the waves may penetrate structures sufficiently for a macrocell to provide service to UEs 115 located indoors. Transmission of UHFwaves may be associated with smaller antennas and shorter range (e.g.,less than 100 km) compared to transmission using the smaller frequenciesand longer waves of the high frequency (HF) or very high frequency (VHF)portion of the spectrum below 300 MHz.

Wireless communications system 100 may also operate in a super highfrequency (SHF) region using frequency bands from 3 GHz to 30 GHz, alsoknown as the centimeter band. The SHF region includes bands such as the5 GHz industrial, scientific, and medical (ISM) bands, which may be usedopportunistically by devices that can tolerate interference from otherusers.

Wireless communications system 100 may also operate in an extremely highfrequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz),also known as the millimeter band. In some aspects, wirelesscommunications system 100 may support millimeter wave (mmW)communications between UEs 115 and base stations 105, and EHF antennasof the respective devices may be even smaller and more closely spacedthan UHF antennas. In some cases, this may facilitate use of antennaarrays within a UE 115 (e.g., for multiple-input multiple-output (MIMO)operations such as spatial multiplexing, or for directionalbeamforming). However, the propagation of EHF transmissions may besubject to even greater atmospheric attenuation and shorter range thanSHF or UHF transmissions. Techniques disclosed herein may be employedacross transmissions that use one or more different frequency regions,and designated use of bands across these frequency regions may differ bycountry or regulating body.

In some aspects, wireless communications system 100 may utilize bothlicensed and unlicensed radio frequency spectrum bands. For example,wireless communications system 100 may employ LTE License AssistedAccess (LTE-LAA) or LTE-Unlicensed (LTE-U) radio access technology or NRtechnology in an unlicensed band such as the 5 GHz ISM band. Whenoperating in unlicensed radio frequency spectrum bands, wireless devicessuch as base stations 105 and UEs 115 may employ listen-before-talk(LBT) procedures to ensure a frequency channel is clear beforetransmitting data. In some cases, operations in unlicensed bands may bebased on a CA configuration in conjunction with CCs operating in alicensed band. Operations in unlicensed spectrum may include downlinktransmissions, uplink transmissions, peer-to-peer transmissions, or acombination of these. Duplexing in unlicensed spectrum may be based onfrequency division duplexing (FDD), time division duplexing (TDD), or acombination of both.

In some cases, the antennas of a base station 105 or UE 115 may belocated within one or more antennas or antenna arrays, which may supportMIMO operations such as spatial multiplexing, or transmit or receivebeamforming. For example, one or more base station antennas or antennaarrays may be co-located at an antenna assembly, such as an antennatower. In some cases, antennas or antenna arrays associated with a basestation 105 may be located in diverse geographic locations. A basestation 105 may have an antenna array with a number of rows and columnsof antenna ports that the base station 105 may use to supportbeamforming of communications with a UE 115. Likewise, a UE 115 may haveone or more antenna arrays that may support various MIMO or beamformingoperations.

MIMO wireless systems use a transmission scheme between a transmittingdevice (e.g., a base station 105) and a receiving device (e.g., a UE115), where both transmitting device and the receiving device areequipped with multiple antennas. MIMO communications may employmultipath signal propagation to increase the utilization of a radiofrequency spectrum band by transmitting or receiving different signalsvia different spatial paths, which may be referred to as spatialmultiplexing. The different signals may, for example, be transmitted bythe transmitting device via different antennas or different combinationsof antennas. Likewise, the different signals may be received by thereceiving device via different antennas or different combinations ofantennas. Each of the different signals may be referred to as a separatespatial stream, and the different antennas or different combinations ofantennas at a given device (e.g., the orthogonal resource of the deviceassociated with the spatial dimension) may be referred to as spatiallayers.

Beamforming, which may also be referred to as spatial filtering,directional transmission, or directional reception, is a signalprocessing technique that may be used at a transmitting device or areceiving device (e.g., a base station 105 or a UE 115) to shape orsteer an antenna beam (e.g., a transmit beam or receive beam) along adirection between the transmitting device and the receiving device.Beamforming may be achieved by combining the signals communicated viaantenna elements of an antenna array such that signals propagating atparticular orientations with respect to an antenna array experienceconstructive interference while others experience destructiveinterference. The adjustment of signals communicated via the antennaelements may include a transmitting device or a receiving deviceapplying certain phase offset, timing advance/delay, or amplitudeadjustment to signals carried via each of the antenna elementsassociated with the device. The adjustments associated with each of theantenna elements may be defined by a beamforming weight set associatedwith a particular orientation (e.g., with respect to the antenna arrayof the transmitting device or receiving device, or with respect to someother orientation).

In one aspect, a base station 105 may multiple use antennas or antennaarrays to conduct beamforming operations for directional communicationswith a UE 115. For instance, signals may be transmitted multiple timesin different directions, which may include a signal being transmittedaccording to different beamforming weight sets associated with differentdirections of transmission. A receiving device (e.g., a UE 115, whichmay be an example of a mmW receiving device) may try multiple receivebeams when receiving various signals from the base station 105, such assynchronization signals or other control signals. For example, areceiving device may try multiple receive directions by receiving viadifferent antenna subarrays, by processing received signals according todifferent antenna subarrays, by receiving according to different receivebeamforming weight sets applied to signals received at a plurality ofantenna elements of an antenna array, or by processing received signalsaccording to different receive beamforming weight sets applied tosignals received at a plurality of antenna elements of an antenna array,any of which may be referred to as “listening” according to differentreceive beams or receive directions.

In some cases, wireless communications system 100 may be a packet-basednetwork that operate according to a layered protocol stack. In the userplane, communications at the bearer or Packet Data Convergence Protocol(PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may insome cases perform packet segmentation and reassembly to communicateover logical channels. A Medium Access Control (MAC) layer may performpriority handling and multiplexing of logical channels into transportchannels. The MAC layer may also use hybrid automatic repeat request(HARQ) to provide retransmission at the MAC layer to improve linkefficiency. In the control plane, the Radio Resource Control (RRC)protocol layer may provide establishment, configuration, and maintenanceof an RRC connection between a UE 115 and a base station 105 or corenetwork 130 supporting radio bearers for user plane data. At thePhysical (PHY) layer, transport channels may be mapped to physicalchannels.

In some cases, UEs 115 and base stations 105 may support retransmissionsof data to increase the likelihood that data is received successfully.HARQ feedback is one technique of increasing the likelihood that data isreceived correctly over a communication link 125. HARQ may include acombination of error detection (e.g., using a cyclic redundancy check(CRC)), forward error correction (FEC), and retransmission (e.g.,automatic repeat request (ARQ)). HARQ may improve throughput at the MAClayer in poor radio conditions (e.g., signal-to-noise conditions). Insome cases, a wireless device may support same-slot HARQ feedback, wherethe device may provide HARQ feedback in a specific slot for datareceived in a previous symbol in the slot. In other cases, the devicemay provide HARQ feedback in a subsequent slot, or according to someother time interval.

Time intervals in LTE or NR may be expressed in multiples of a basictime unit, which may, for example, refer to a sampling period ofTs=1/30,720,000 seconds. Time intervals of a communications resource maybe organized according to radio frames each having a duration of 10milliseconds (Tf=307200*Ts). The radio frames may be identified by asystem frame number (SFN) ranging from 0 to 1023. Each frame may includeten subframes numbered from 0 to 9, and each subframe may have aduration of 1 millisecond. A subframe may be further divided into twoslots each having a duration of 0.5 milliseconds, and each slot maycontain 6 or 7 modulation symbol periods (e.g., depending on the lengthof the cyclic prefix prepended to each symbol period). Excluding thecyclic prefix, each symbol period may contain 2048 sampling periods. Insome cases a subframe may be the smallest scheduling unit of thewireless communications system 100, and may be referred to as atransmission time interval (TTI). In other cases, a smallest schedulingunit of the wireless communications system 100 may be shorter than asubframe or may be dynamically selected (e.g., in bursts of shortenedTTIs (sTTIs) or in selected component carriers using sTTIs).

In some wireless communications systems, a slot may further be dividedinto multiple mini-slots containing one or more symbols and in someinstances, a symbol of a mini-slot or a mini-slot may be the smallestunit of scheduling. Each symbol may vary in duration depending on thesubcarrier spacing or frequency band of operation, for example. Somewireless communications systems may implement slot aggregation in whichmultiple slots or mini-slots may be aggregated together forcommunication between a UE 115 and a base station 105.

A resource element may consist of one symbol period (e.g., a duration ofone modulation symbol) and one subcarrier (e.g., a 15 kHz frequencyrange). A resource block may contain 12 consecutive subcarriers in thefrequency domain (e.g., collectively forming a “carrier”) and, for anormal cyclic prefix in each orthogonal frequency-division multiplexing(OFDM) symbol, 7 consecutive OFDM symbol periods in the time domain (1slot), or 84 total resource elements across the frequency and timedomains. The number of bits carried by each resource element may dependon the modulation scheme (the configuration of modulation symbols thatmay be applied during each symbol period). Thus, the more resourceelements that a UE 115 receives and the higher the modulation scheme(e.g., the higher the number of bits that may be represented by amodulation symbol according to a given modulation scheme), the higherthe data rate may be for the UE 115. In MIMO systems, a wirelesscommunications resource may refer to a combination of a radio frequencyspectrum band resource, a time resource, and a spatial resource (e.g.,spatial layers), and the use of multiple spatial layers may furtherincrease the data rate for communications with a UE 115.

The term “carrier” refers to a set of radio frequency spectrum resourceshaving a defined organizational structure for supporting uplink ordownlink communications over a communication link 125. For example, acarrier of a communication link 125 may include a portion of a radiofrequency spectrum band that may also be referred to as a frequencychannel. In some aspects a carrier may be made up of multiplesub-carriers (e.g., waveform signals of multiple different frequencies).A carrier may be organized to include multiple physical channels, whereeach physical channel may carry user data, control information, or othersignaling.

The organizational structure of the carriers may be different fordifferent radio access technologies (e.g., LTE, LTE-A, NR, etc.). Forexample, communications over a carrier may be organized according toTTIs or slots, each of which may include user data as well as controlinformation or signaling to support decoding the user data. A carriermay also include dedicated acquisition signaling (e.g., synchronizationsignals or system information, etc.) and control signaling thatcoordinates operation for the carrier. In some aspects (e.g., in acarrier aggregation configuration), a carrier may also have acquisitionsignaling or control signaling that coordinates operations for othercarriers.

Physical channels may be multiplexed on a carrier according to varioustechniques. A physical control channel and a physical data channel maybe multiplexed on a downlink carrier, for example, using time divisionmultiplexing (TDM) techniques, frequency division multiplexing (FDM)techniques, or hybrid TDM-FDM techniques. In some aspects, controlinformation transmitted in a physical control channel may be distributedbetween different control regions in a cascaded manner (e.g., between acommon control region or common search space and one or more UE-specificcontrol regions or UE-specific search spaces).

A carrier may be associated with a particular bandwidth of the radiofrequency spectrum, and in some aspects the carrier bandwidth may bereferred to as a “system bandwidth” of the carrier or the wirelesscommunications system 100. For example, the carrier bandwidth may be oneof a number of predetermined bandwidths for carriers of a particularradio access technology (e.g., 1.4, 3, 5, 10, 15, or 20 MHz). In someaspects the system bandwidth may refer to a minimum bandwidth unit forscheduling communications between a base station 105 and a UE 115. Inother aspects a base station 105 or a UE 115 may also supportcommunications over carriers having a smaller bandwidth than the systembandwidth. In such aspects, the system bandwidth may be referred to as“wideband” bandwidth and the smaller bandwidth may be referred to as a“narrowband” bandwidth. In some aspects of the wireless communicationssystem 100, wideband communications may be performed according to a 20MHz carrier bandwidth and narrowband communications may be performedaccording to a 1.4 MHz carrier bandwidth.

Devices of the wireless communications system 100 (e.g., base stationsor UEs 115) may have a hardware configuration that supportscommunications over a particular carrier bandwidth, or may beconfigurable to support communications over one of a set of carrierbandwidths. For example, base stations 105 or UEs 115 may perform somecommunications according to a system bandwidth (e.g., widebandcommunications), and may perform some communications according to asmaller bandwidth (e.g., narrowband communications). In some aspects,the wireless communications system 100 may include base stations 105and/or UEs that can support simultaneous communications via carriersassociated with more than one different bandwidth.

Wireless communications system 100 may support communication with a UE115 on multiple cells or carriers, a feature which may be referred to ascarrier aggregation (CA) or multi-carrier operation. A UE 115 may beconfigured with multiple downlink CCs and one or more uplink CCsaccording to a carrier aggregation configuration. Carrier aggregationmay be used with both FDD and TDD component carriers.

In some cases, wireless communications system 100 may utilize enhancedcomponent carriers (eCCs). An eCC may be characterized by one or morefeatures including wider carrier or frequency channel bandwidth, shortersymbol duration, shorter TTI duration, or modified control channelconfiguration. In some cases, an eCC may be associated with a carrieraggregation configuration or a dual connectivity configuration (e.g.,when multiple serving cells have a suboptimal or non-ideal backhaullink). An eCC may also be configured for use in unlicensed spectrum orshared spectrum (e.g., where more than one operator is allowed to usethe spectrum). An eCC characterized by wide carrier bandwidth mayinclude one or more segments that may be utilized by UEs 115 that arenot capable of monitoring the whole carrier bandwidth or are otherwiseconfigured to use a limited carrier bandwidth (e.g., to conserve power).

In some cases, an eCC may utilize a different symbol duration than otherCCs, which may include use of a reduced symbol duration as compared withsymbol durations of the other CCs. A shorter symbol duration may beassociated with increased spacing between adjacent subcarriers. Adevice, such as a UE 115 or base station 105, utilizing eCCs maytransmit wideband signals (e.g., according to frequency channel orcarrier bandwidths of 20, 40, 60, 80 MHz, etc.) at reduced symboldurations (e.g., 16.67 microseconds). A TTI in eCC may consist of one ormultiple symbol periods. In some cases, the TTI duration (that is, thenumber of symbol periods in a TTI) may be variable.

Wireless communications systems such as an NR system may use acombination of licensed, shared, and unlicensed spectrum bands, amongothers. The flexibility of eCC symbol duration and subcarrier spacingmay allow for the use of eCC across multiple spectrums. In some aspects,NR shared spectrum may increase spectrum utilization and spectralefficiency, specifically through dynamic vertical (e.g., acrossfrequency) and horizontal (e.g., across time) sharing of resources.

In some cases, UE 115 may be configured with multiple antennas tocommunicate with base station 105. In one aspect, UE 115 may use a firstantenna to communicate with base station 105 while a second antenna ofUE 115 is not used. UE 115 may determine to switch to using the secondantenna, instead of the first antenna, to communicate with base station105. UE 115 may opportunistically schedule the switch from the firstantenna to the second antenna to coincide with a silence window in whichcommunication with base station 105 will be suspended. In anotheraspect, UE 115 may communicate with base station 105 using multipleantennas simultaneously (e.g., as in downlink MIMO (DL-MIMO) and/oruplink MIMO (UL-MIMO)) while other antennas of UE 115 are not used. UE115 may determine to switch to from the used antennas to the unusedantennas to communicate with base station 105 and may opportunisticallyschedule the switches to occur during a silence window. Furtherdescription of scheduling antenna switching is described below.

FIG. 2 illustrates a block diagram of various components of a UE 115that supports antenna switch scheduling in accordance with variousaspects of the present disclosure. FIG. 2 is one example configurationof UE 115, and other multi-antenna configurations of UE 115 arecontemplated to be within the scope of the disclosure. In one aspect, UE115 utilizes ASDIV. UE 115 includes a first antenna (ANT1) 205 a and asecond antenna (ANT2) 205 b coupled to a switch component 215. In oneaspect, first antenna 205 a and second antenna 205 b may be in differentareas of UE 115 (e.g., one at a bottom area of UE 115 and one at a toparea of UE 115). Although two antennas are depicted, skilled artisanswill recognize that more than two antennas may be implemented. Switch215 is operable to couple and decouple first antenna 205 a and secondantenna 205 b to other components of UE 115. Although switch 215 isrepresented by a single block in FIG. 2, switch 215 may include multipleswitches and/or components.

A filter component 220 is coupled to switch 215 and may be configured topass signals of selected frequencies. Although filter 220 is representedby a single block in FIG. 2, filter 220 may include multiple filtersand/or components. Filter 220 may be coupled to a transmit (TX) chain225 that includes one or more power amplifiers 230 and other signalconditioning components/circuitry (e.g., mixers, amplifiers, filters)235. Filter 220 may also be coupled to a receive (RX) chain 240 thatincludes one or more low noise amplifiers (LNAs) 245 and other signalconditioning components/circuitry (e.g., automatic gain control (AGC),mixers, amplifiers, filters) 250. LNA(s) 245 may include built-in AGCfunctionality. Transmit chain 225 and receive chain 240 are coupled toone or more processors 255 (e.g, a modem). Processor 255 is coupled toswitch 215 (represented by control line 260) and may control switchingoperations to select an antenna for communication with a base station105.

In one aspect, UE 115 may be configured to operate in amulti-connectivity mode (e.g., an E-UTRA New Radio-Dual Connectivity(EN-DC) mode) in which one or both antennas 205 a, 205 b are configuredto transmit and/or receive signals corresponding to multiple radioaccess technologies (RATs). In the multi-connectivity mode, UE 115 mayshare switch 215 between RATs, and the RATs may either share otherfront-end components (e.g., filters, amplifiers, mixers) or haveseparate front-end components or chains. In another aspect, UE 115 maybe configured to operate in carrier aggregation (CA) mode using multiplecarriers. In CA mode, UE 115 may share switch 215 among carriers and thecarriers may either share other front-end components (e.g., filters,amplifiers, mixers) or have separate front-end components or chains.

Processor 255 may employ any number of different methodologies fordetermining the antenna(s) to use for transmitting and/or receiving. Inone aspect, processor 255 may use communication metrics corresponding todownlink signal conditions, uplink signal conditions, or a combinationthereof to determine the antenna(s) to use. In one aspect, processor 225may use receive signal strength metrics (e.g., receive signal strengthindicator (RSSI), reference signal receive power (RSRP), referencesignal receive quality (RSRQ), or other signal-to-noise (SNR) metrics).In one aspect, processor 225 may use UL transmission metrics, such asmaximum transmit power limit (MTPL), power headroom (which may varybased on modulation and coding schemes (MCS)), and specific absorptionrate (SAR) backoff metrics. In one aspect, processor 255 may usecommunication metrics filtered over time (e.g., an average metric overtime). In one aspect, processor 255 may determine to switch from oneantenna to another antenna when a difference between RSRP (RSRPDelta) ofthe antennas is greater than a threshold value (e.g., 3 dB), when theaverage RSRPDelta is greater than a threshold, and/or when the MTPL hasbeen reached for some percentage of a time period.

ASDIV may involve suspending current transmissions of transmit chain 225and/or suspending or disabling receive chain 240 components during aswitch between antennas (e.g., from first antenna 205 a to secondantenna 205 b). Transmissions on transmit chain 225 may need to beblanked or suspended to avoid damaging one or more components, such aspower amplifier(s) 230. Receive chain 240 components, such as LNA(s) 245and AGC components, may need to be suspended or disabled to change AGCand digital controlled variable gain amplifier (DVGA) settings oroffsets to account for changing ASDIV configuration settings. In oneaspect, processor 255 determines whether a silence window will occur incommunications with a base station 105 and whether to wait for thesilence window to switch antennas.

FIG. 3 illustrates a block diagram of various portions of a UE 115 thatsupports antenna switch scheduling for MIMO (e.g., DL-MIMO, UL-MIMO)applications in accordance with various aspects of the presentdisclosure. FIG. 3 is one example configuration of UE 115, and othermulti-antenna configurations of UE 115 are contemplated to be within thescope of the disclosure. UE 115 includes a first antenna (ANT1) 305 a, asecond antenna (ANT2) 305 b, a third antenna (ANT3) 305 c, and a fourthantenna (ANT4) 305 d coupled to a switch component 315. Although fourantennas are depicted, skilled artisans will recognize that more thanfour antennas may be implemented. In one aspect, the antennas may be indifferent areas of UE 115. Switch 315 is operable to couple and decouplefirst antenna 305 a, second antenna 305 b, third antenna 305 c andfourth antenna 305 d to other components of UE 115. Although switch 315is represented by a single block in FIG. 3, switch 315 may includemultiple switches or components.

In MIMO applications, multiple ones of antennas 305 a-305 d may transmitand/or receive simultaneously. For example, in UL-MIMO signals fortransmission on a first path (or chain) 320 may be routed to a first oneof antennas 305 a-305 d and signals for transmission on a second path(or chain) 330 may be routed to a second one of antennas 305 a-305 d. Ina DL-MIMO example, signals received on a first one of antennas 305 a-305d may be routed to first path 320 and signals received on a second oneof antennas 305 a-305 d may be routed to second path 330. First andsecond paths 320 and 330 may include various components that are part oftransmission and/or receive chains.

UE 115 may include one or more processors 355 coupled to paths 320, 330and to switch 315 via a control line 360 to control the routing of paths320, 330 to the various antennas 305 a-305 d. Processor 355 maydetermine metrics (as described with reference to FIG. 2) associatedwith each antenna 305 a-305 d and select an antenna for each path 320,330 based on the metrics. Processor 355 may also determine to reroutepath 320 and/or 330 to a different antenna based on the metrics.Processor 355 may determine to switch antennas for each path 320, 330independently. For example, path 320 may be routed to first antenna 305a and path 330 may be routed to second antenna 305 b, and processor 355may determine to reroute path 320 to third antenna 305 c while path 330remains routed to second antenna 305 b. In one aspect, processor 355determines whether a silence window will occur in communications with abase station 105 and whether to wait for the silence window to switchantennas for one or both paths 320, 330.

UE 115 of FIG. 3 may be configured to operate in a multi-connectivitymode (e.g., EN-DC mode) in which one or multiple ones of antennas 205a-205 d are configured to transmit and/or receive signals correspondingto multiple RATs. In the multi-connectivity mode, UE 115 may shareswitch 315 between RATs, and the RATs may either share other front-endcomponents (e.g., filters, amplifiers, mixers) or have separatefront-end components or chains. UE 115 of FIG. 3 may be configured tooperate in CA mode in which one or multiple ones of antennas 205 a-205 dare configured to transmit and/or receive signals corresponding tomultiple carriers.

FIG. 4 is illustrates a timeline diagram 400 of operations of UE 115that supports antenna switch scheduling in accordance with aspects ofthe present disclosure. Timeline 400 is one aspect of operations thatmay be performed by UE 115. Other operations in accordance with thedisclosure and other orders of operations may be executed by UE 115. Theoperations depicted in timeline 400 may be performed and/or executed bya processor (e.g., processor 255, processor 355) and switch (e.g.,switch 215, switch 315).

At t1, UE 115 detects a switch condition by determining to switchcommunication from a first antenna to a second antenna. For example, afirst antenna that is being used to communicate with a base station 105may experience degraded channel conditions (e.g., degraded channelconditions due to blockage by a user's hand or head). A second antennathat is not being used for communication may have better channelconditions than the first antenna (e.g., the second antenna may be in adifferent location of the UE 115 and may experience no or less blockagethan the first antenna). In some aspects, UE 115 may determinecommunication metrics (e.g., DL and/or UL metrics) associated with itsantennas to determine whether to switch from a first antenna to a secondantenna to communicate with base station 105. In one aspect, UE 115 mayuse a combination of DL and UL metrics to detect a switch condition.

Some example communication metrics are described with reference to FIG.2. In one aspect, UE 115 may determine RSRP metrics for the first andsecond antennas. The switch condition may correspond to RSRPDelta (oraverage RSRPDelta) exceeding a threshold. In another aspect, UE 115 maydetermine whether the MTPL for the first antenna has been reached for athreshold percentage of a time period and use this determination incombination with an RSRP determination to detect a switch condition. Insome aspects, UE 115 may periodically evaluate communication metrics todetermine whether to switch antennas and ASDIV configurations. As oneexample, UE 115 may evaluate communication metrics every 640 ms.

At t2, UE 115 determines whether a silence window 405 will occur andwhether to schedule the antenna switch to take place during silencewindow 405. In FIG. 4, t2 is depicted as occurring some time after t1(the switch detection). However, the operations of t2 may occur directlyafter detecting a switch condition or simultaneously with detecting aswitch condition. Silence window 405 may correspond to various differenttypes of time durations in which communications between UE 115 and basestation 105 will be suspended. For example, silence window 405 maycorrespond to a measurement gap duration, a connected mode discontinuousreception (CDRX) or discontinuous transmission (DTX) off (e.g., sleep)state duration, and/or a silence interval in voice communications. Insome aspects, UE 115 may be configured to operate in amulti-connectivity mode or CA mode, and silence window 405 maycorrespond to a time duration in which communication with basestation(s) 105 is suspended for multiple RATs or multiple carriers. Asilence window may be determined using various techniques including byanalyzing control information or parameters determined by UE 115 orsignaled to UE 115 from a network.

In some scenarios, the channel conditions of a first antenna that isbeing used for communications with base station 105 may be degraded to apoint where UE 115 may determine to switch to a second antenna beforewaiting for silence window 405. For example, the channel conditionsrelated to the first antenna may be such that UE 115 may lose connectionwith base station 105 before silence window 405 occurs. UE 115 may usethe communication metrics (e.g., DL and/or UL metrics) to determinewhether to wait for silence window 405 to switch antennas. In oneaspect, UE 115 may compare communication metrics to a first threshold att1 to determine whether to switch antennas and may compare thecommunication metrics to a second threshold at t2 to determine whetherto wait for silence window 405 to switch antennas. In an aspect, thecommunication metrics may correspond to RSRPDelta and the firstthreshold may correspond to a first dB level (e.g., 3 dB) and the secondthreshold may correspond to a second dB level greater than the first dBlevel (e.g., 2 dB greater than the first dB level, or 5 dB). UE 115 maydetermine to switch antennas, and wait for silence window 405 to switch,if RSRPDelta exceeds the first threshold but does not exceed the secondthreshold. If RSRPDelta exceeds the first and second thresholds, UE 115may switch antennas without waiting for silence window 405 to do so.

UE 115 may also factor in the length of time between detecting a switchcondition and the start of silence window (e.g., from t1 to t3) todetermine whether to wait for silence window 405 to switch. If thelength of time between t1 and t3 exceeds a threshold time, UE 115 maydetermine to switch before silence window 405. UE 115 may use acombination of communication metrics and time metrics to determinewhether to wait for silence window 405 to switch. In an aspect, UE 115may compare communication metrics to thresholds (e.g., a first thresholdand a second threshold) and compare the time until the next silencewindow 405 to determine whether to wait for silence window 405 toswitch.

The switch from a first antenna to a second antenna may not occurinstantaneously. Instead, various settings and/or offsets may need tochange and signals to components may need to be suspended in preparationto switch, which may take some time. The length of time from initiatingthe switch (e.g., suspending signals, initiating the change of settings)to completing the switch of antennas may be referred to as a switchduration. UE 115 may compare the switch duration to a silence duration,which corresponds to a length of time of silence window 405 (e.g., thelength of time between t3 and t6), to determine whether silence durationof silence window 405 is long enough to accommodate the switch (e.g.,whether the silence duration is equal to or greater than the switchduration). If the silence duration is greater than or equal to theswitch duration, UE 115 may schedule the switch to occur during thesilence duration.

As depicted in FIG. 4, UE 115 determines to schedule the antenna switchto occur during silence window 405, which starts at t3 and ends at t6.UE 115 begins to switch from a first antenna to a second antenna at t4and ends the switch at t5. Although t4 is depicted in FIG. 4 asoccurring after t3, t4 may coincide with t3. That is, UE 115 may beginthe antenna switch at the start of silence window 405.

FIG. 5 is illustrates a timeline diagram 500 of operations of UE 115that supports antenna switch scheduling in accordance with aspects ofthe present disclosure. Timeline 500 is one aspect of operations thatmay be performed by UE 115. Other operations in accordance with thedisclosure and other orders of operations may be executed by UE 115. Theoperations depicted in timeline 500 may be performed and/or executed bya processor (e.g., processor 255, processor 355) and switch (e.g.,switch 215, switch 315).

In FIG. 5, silence windows (e.g., as described with reference to FIG. 4)correspond to measurement gaps such as gaps 505 a, 505 b and 505 c. Insome aspects, gaps 505 a-505 c may correspond to per-UE measurementgaps. Gaps 505 a-505 c may occur periodically such as every 40 ms, 80ms, 160 ms or other periodicities. In multi-connectivity scenarios, suchas EN-DC, or CA scenarios measurement gaps may correspond to commonmeasurement gaps (e.g., shared measurement gaps) for the multiple RATsor the multiple carriers. At t1, UE 115 detects a switch condition bydetermining to switch communication from a first antenna to a secondantenna. As depicted in FIG. 5, t1 occurs after first gap 505 a.

At t2, UE 115 determines whether second gap 505 b will occur and whetherto schedule the antenna switch to take place during second gap 505 b. UE115 may analyze various factors (e.g., described with reference to FIG.4), such as communication metrics, a silence duration (e.g., theduration of gap 505 b), a switch duration, and a length of time betweenthe switch detection and the start of second gap 505 b to determinewhether to schedule the antenna switch during second gap 505 b.

As depicted in FIG. 5, UE 115 determines to schedule the antenna switchto occur during second gap 505 b, which starts at t3 and ends at t6. UE115 begins to switch from a first antenna to a second antenna at t4 andends the switch at t5. Although t4 is depicted in FIG. 5 as occurringafter t3, t4 may coincide with t3. That is, UE 115 may begin the antennaswitch at the start of second gap 505 b. The antenna switch duringsecond gap 505 b may include changing ASDIV configurations. In anaspect, prior to second gap 505 b the ASDIV configuration may be a firstconfiguration (e.g., ASDIV config-0) and after second gap 505 b theASDIV configuration may be a second configuration (e.g., ASDIVconfig-1). The ASDIV configuration change may be scheduled to occurduring second gap 505 b and may preempt other changes or measurementsduring second gap 505 b.

FIG. 6 is illustrates a timeline diagram 600 of operations of UE 115that supports antenna switch scheduling in accordance with aspects ofthe present disclosure. Timeline 600 is one aspect of operations thatmay be performed by UE 115. Other operations in accordance with thedisclosure and other orders of operations may be executed by UE 115. Theoperations depicted in timeline 600 may be performed and/or executed bya processor (e.g., processor 255, processor 355) and switch (e.g.,switch 215, switch 315).

In FIG. 6, a silence window (e.g., as described with reference to FIG.4) corresponds to a DRX and/or DTX (e.g., CDRX) OFF or sleep duration605 in a DRX cycle. DRX OFF duration 605 may occur periodicallyaccording to the DRX cycle and may follow a DRX ON or awake duration 610a. As shown in FIG. 6, the DRX cycle spans from t1 to t7 with ONduration 610 a spanning from t1 to t4 and OFF duration 605 spanning fromt4 to t7. At t2, UE 115 detects a switch condition by determining toswitch communication from a first antenna to a second antenna. Asdepicted in FIG. 6, t2 occurs during ON duration 610 a.

At t3, UE 115 determines whether to schedule the antenna switch to takeplace during OFF duration 605. UE 115 may analyze various factors (e.g.,described with reference to FIG. 4), such as communication metrics, asilence duration (e.g., the length of OFF duration 605), a switchduration, and a length of time between the switch detection and thestart of OFF duration 605 to determine whether to schedule the antennaswitch during OFF duration 605. In one aspect, UE 115 may schedule theantenna switch to occur during OFF duration 605 if the time betweendetecting the switch condition and the start of OFF duration 605 is 100ms or less.

As depicted in FIG. 6, UE 115 determines to schedule the antenna switchto occur during OFF duration 605. UE 115 begins to switch from a firstantenna to a second antenna at t5 and ends the switch at t6. Although t5is depicted in FIG. 6 as occurring after t4 (the start of OFF duration605), t5 may coincide with t4. That is, UE 115 may begin the antennaswitch at the start of OFF duration 605. Once UE 115 finishes theantenna switch at t6, UE 115 may sleep for the remainder of OFF duration605. The antenna switch during OFF duration 605 may include changingASDIV configurations. In an aspect, during ON duration 610 a the ASDIVconfiguration may be a first configuration (e.g., ASDIV config-0) andduring an ON duration 610 b the ASDIV configuration may be a secondconfiguration (e.g., ASDIV config-1).

FIG. 7 is illustrates a timeline diagram 700 of operations of UE 115that supports antenna switch scheduling in a multi-connectivity mode inaccordance with aspects of the present disclosure. Timeline 700 is oneaspect of operations that may be performed by UE 115. Other operationsin accordance with the disclosure and other orders of operations may beexecuted by UE 115. The operations depicted in timeline 700 may beperformed and/or executed by a processor (e.g., processor 255, processor355) and switch (e.g., switch 215, switch 315).

In FIG. 7, a silence window 702 corresponds to overlapping portions of aDRX OFF duration 705 a of a first RAT (RAT1) and a DRX OFF duration 705b of a second RAT (RAT2). In a multi-connectivity mode, such as an EN-DCmode, DRX cycles of the different RATs may not be synchronized in timeand may have ON and/or OFF durations of different lengths. UE 115 maydetermine DRX cycle information for each RAT and identify portions ofDRX OFF durations that overlap in time based on the information.

At t1, UE 115 detects a switch condition by determining to switchcommunication from a first antenna to a second antenna. At t2, UE 115determines whether to schedule the antenna switch to take place duringsilence window 702, which corresponds to the overlapping portions of OFFdurations 705 a and 705 b. UE 115 may analyze various factors (e.g.,described with reference to FIG. 4), such as communication metrics, asilence duration (e.g., the duration of silence window 702), a switchduration, and a length of time between the switch detection and thestart of silence window 702 to determine whether to schedule the antennaswitch during silence window 702. In one aspect, UE 115 may schedule theantenna switch to occur during silence window 702 if the time betweendetecting the switch condition and the start of silence window 702 is100 ms or less.

As depicted in FIG. 7, UE 115 determines to schedule the antenna switchto occur during silence window 702. UE 115 begins to switch from a firstantenna to a second antenna at t4 and ends the switch at t5. Although t4is depicted in FIG. 7 as occurring after t3 (the start of silence window702), t4 may coincide with t3. That is, UE 115 may begin the antennaswitch at the start of silence window 702. Once UE 115 finishes theantenna switch at t5, UE 115 may sleep for the remainder of silencewindow 702 (e.g., until t6).

FIG. 8 is illustrates a timeline diagram 800 of operations of UE 115that supports antenna switch scheduling in accordance with aspects ofthe present disclosure. Timeline 800 is one aspect of operations thatmay be performed by UE 115. Other operations in accordance with thedisclosure and other orders of operations may be executed by UE 115. Theoperations depicted in timeline 800 may be performed and/or executed bya processor (e.g., processor 255, processor 355) and switch (e.g.,switch 215, switch 315).

In FIG. 8, a silence window corresponds to a silence interval 805 thatmay occur in a voice type or voice related service. During voice relatedservices, a voice activity factor may correspond to an average time thatvoice is communicated between users. In one aspect, the voice activityfactor may be around 40%. During inactivity a voice vocoder may send asilence indicator descriptor (SID) vocoder packet 810 a at the beginningof a silence occasion and may send other SID packets (e.g., packet 810b) at selected intervals (e.g., every 160 ms). Silence interval 805 maycorrespond to the time between SID packets 810 a and 810 b.

At t0, UE 115 may determine that an active service is a voice relatedservice. At t1, UE 115 may determine (e.g., through a voice activitydetection algorithm) that a condition is met to enter a voice silenceperiod or occasion and may start to send SID packet 810 a at t3.Although t3 is depicted in FIG. 8 as occurring after t1, t3 may coincidewith t1. That is, SID packet 810 a may be sent immediately when thevoice activity detection algorithm detects silence.

At t2, UE 115 detects a switch condition by determining to switchcommunication from a first antenna to a second antenna. At t2, UE 115determines whether to schedule the antenna switch to take place duringsilence interval 805. UE 115 may analyze various factors (e.g.,described with reference to FIG. 4), such as communication metrics, asilence duration (e.g., the duration of silence interval 805), a switchduration, and a length of time between the switch detection and thestart of silence interval 805 to determine whether to schedule theantenna switch during silence interval 805. Although t2 is depicted asoccurring after t1, UE 115 may detect a switch condition at the sametime as detecting voice silence or before detecting voice silence. Inone aspect, UE 115 may detect a switch condition before detecting voicesilence and may wait for a selected time period to detect voice silence.If voice silence is not detected within the selected time period, UE 115may begin the antenna switch. If voice silence is detected within theselected time period, UE 115 may determine to schedule the antennaswitch to occur during silence interval 805.

As depicted in FIG. 8, UE 115 determines to schedule the antenna switchto occur during silence interval 805. UE 115 begins to switch from afirst antenna to a second antenna at t5 and ends the switch at t6 beforethe communication of the next SID packet 810 b at t7. Although t5 isdepicted in FIG. 8 as occurring after t4 (the end of SID packet 810 a),t5 may coincide with t4. That is, UE 115 may begin the antenna switchimmediately after communication of SID packet 810 a.

FIG. 9 shows a block diagram 900 of a wireless device 905 that supportsantenna switch scheduling in a multi-antenna UE in accordance withaspects of the present disclosure. Wireless device 905 may be an exampleof aspects of a user equipment (UE) 115 as described herein. Wirelessdevice 905 may include receiver 910, UE communications manager 915, andtransmitter 920. Wireless device 905 may also include a processor. Eachof these components may be in communication with or coupled to oneanother (e.g., via one or more buses).

Receiver 910 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, etc.). Information may be passed on toother components of the device. The receiver 910 may utilize a singleantenna or a set of antennas. Receiver 910 may be an example of aspectsof components described with reference to FIGS. 2 and 3 and thetransceiver 1035 described with reference to FIG. 10.

UE communications manager 915 and/or at least some of its varioussub-components may be implemented in hardware, software executed by aprocessor, firmware, or any combination thereof. If implemented insoftware executed by a processor, the functions of the UE communicationsmanager 915 and/or at least some of its various sub-components may beexecuted by a general-purpose processor, a digital signal processor(DSP), an application-specific integrated circuit (ASIC), anfield-programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described in thepresent disclosure. UE communications manager 915 and/or at least someof its various sub-components may be physically located at variouspositions, including being distributed such that portions of functionsare implemented at different physical locations by one or more physicaldevices. In some aspects, UE communications manager 915 and/or at leastsome of its various sub-components may be a separate and distinctcomponent in accordance with various aspects of the present disclosure.In other aspects, UE communications manager 915 and/or at least some ofits various sub-components may be combined with one or more otherhardware components, including but not limited to an I/O component, atransceiver, a network server, another computing device, one or moreother components described in the present disclosure, or a combinationthereof in accordance with various aspects of the present disclosure. UEcommunications manager 915 may be an example of aspects of the UEcommunications manager 1015 described with reference to FIG. 10,processor 255 described with reference to FIG. 2, and/or processor 355described with reference to FIG. 3.

UE communications manager 915 may determine whether to switch from afirst antenna to a second antenna to communicate (e.g., transmit and/orreceive) with a base station, determine whether a silence window willoccur, determine whether to wait for the silence window to perform theantenna switch, and perform the antenna switch as described herein.

Transmitter 920 may transmit signals generated by other components ofthe device. In some aspects, transmitter 920 may be collocated withreceiver 910 in a transceiver module. Transmitter 920 may be an exampleof aspects of the components described with reference to FIGS. 2 and 3and the transceiver 1035 described with reference to FIG. 10.Transmitter 920 may utilize a single antenna or a set of antennas.

FIG. 10 shows a diagram of a system 1000 including a device 1005 thatsupports antenna switch scheduling in a multi-antenna UE in accordancewith aspects of the present disclosure. Device 1005 may be an example ofor include the components of wireless device 905, or a UE 115 asdescribed herein. Device 1005 may include components for bi-directionalvoice and data communications including components for transmitting andreceiving communications, including UE communications manager 1015,processor 1020, memory 1025, software 1030, transceiver 1035, antenna1040, and I/O controller 1045. These components may be in electroniccommunication or coupled to each other via one or more buses (e.g., bus1010). Device 1005 may communicate wirelessly with one or more basestations 105.

Processor 1020 may include an intelligent hardware device, (e.g., ageneral-purpose processor, a DSP, a central processing unit (CPU), amicrocontroller, an ASIC, an FPGA, a programmable logic device, adiscrete gate or transistor logic component, a discrete hardwarecomponent, or any combination thereof). In some cases, processor 1020may be configured to operate a memory array using a memory controller.In other cases, a memory controller may be integrated into processor1020. Processor 1020 may be configured to execute computer-readableinstructions stored in a memory to perform various functions (e.g.,functions or tasks supporting antenna switch scheduling in amulti-antenna UE).

Memory 1025 may include random access memory (RAM) and read only memory(ROM). Memory 1025 may store computer-readable, computer-executablesoftware 1030 including instructions that, when executed, cause theprocessor to perform various functions described herein. In some cases,memory 1025 may contain, among other things, a basic input/output system(BIOS) which may control basic hardware or software operation such asthe interaction with peripheral components or devices.

Software 1030 may include code to implement aspects of the presentdisclosure, including code to support antenna switch scheduling in amulti-antenna UE. Software 1030 may be stored in a non-transitorycomputer-readable medium such as system memory or other memory. In somecases, software 1030 may not be directly executable by the processor butmay cause a computer (e.g., when compiled and executed) to performfunctions described herein.

Transceiver 1035 may communicate bi-directionally, via one or moreantennas, wired, or wireless links as described above. In an aspect,transceiver 1035 may represent a wireless transceiver and maycommunicate bi-directionally with another wireless transceiver.Transceiver 1035 may also include a modem to modulate the packets andprovide the modulated packets to the antennas for transmission, and todemodulate packets from signals received from the antennas.

Device may have more than one antenna 1040, which may be capable ofconcurrently transmitting or receiving multiple wireless transmissions.FIGS. 2 and 3 include examples of some of the components or parts thatmay be included in transceiver 1035.

I/O controller 1045 may manage input and output signals for device 1005.I/O controller 1045 may also manage peripherals not integrated intodevice 1005. In some cases, I/O controller 1045 may represent a physicalconnection or port to an external peripheral. In some cases, I/Ocontroller 1045 may utilize an operating system such as iOS®, ANDROID®,MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, LINUX®, or another known operatingsystem. In other cases, I/O controller 1045 may represent or interactwith a modem, a keyboard, a mouse, a touchscreen, or a similar device.In some cases, I/O controller 1045 may be implemented as part of aprocessor. In some cases, a user may interact with device 1005 via I/Ocontroller 1045 or via hardware components controlled by I/O controller1045.

FIG. 11 shows a flowchart illustrating a method 1100 for antenna switchscheduling in a multi-antenna UE in accordance with aspects of thepresent disclosure. The operations of method 1100 may be implemented bya UE 115 or its components as described herein. In an aspect, theoperations of method 1100 may be performed by a UE communicationsmanager as described with reference to FIGS. 9 and 10 and/or a processordescribed with reference to FIGS. 2 and 3. In some aspects, a UE 115 mayexecute a set of codes to control the functional elements of the deviceto perform the functions described below. Additionally or alternatively,the UE 115 may perform aspects of the functions described below usingspecial-purpose hardware.

At block 1105, UE 115 may communicate (e.g., transmit and/or receivesignals) with a base station 105 using a first antenna. The operationsof block 1105 may be performed according to the methods describedherein. In certain examples, aspects of the operations of block 1105 maybe performed by a transceiver, receiver, transmitter, processor, and/orUE communications manager as described herein.

At block 1110, UE 115 may determine to switch from the first antenna toa second antenna for communicating with the base station 105. Theoperations of block 1110 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations ofblock 1110 may be performed by a UE communications manager and/or aprocessor as described herein.

At block 1115, UE 115 may determine whether a silence window will occurin which communication with base station 105 is suspended. Theoperations of block 1115 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations ofblock 1115 may be performed by a UE communications manager and/or aprocessor as described herein.

At block 1120, UE 115 may schedule the switch from the first antenna tothe second antenna to occur during the silence window. The operations ofblock 1120 may be performed according to the methods described herein.In certain examples, aspects of the operations of block 1115 may beperformed by a UE communications manager and/or a processor as describedherein. In one aspect, the operations of block 1120 may be performedaccording to the method 1200 described with reference to FIG. 12.

At block 1125, UE 115 may switch from the first antenna to the secondantenna during the silence window. The operations of block 1115 may beperformed according to the methods described herein. In certainexamples, aspects of the operations of block 1115 may be performed by aUE communications manager, a processor, a transceiver, a receiver,and/or a transmitter as described herein.

FIG. 12 shows a flowchart illustrating a method 1200 for scheduling anantenna switch in a multi-antenna UE in accordance with aspects of thepresent disclosure. The operations of method 1200 may be implemented bya UE 115 or its components as described herein. In an aspect, theoperations of method 1200 may be performed by a UE communicationsmanager or a processor of a UE 115 as described herein. In some aspects,UE 115 may execute a set of codes to control the functional elements ofthe device to perform the functions described below. Additionally oralternatively, UE 115 may perform aspects of the functions describedbelow using special-purpose hardware.

At block 1205, UE 115 determines whether communication metricsassociated with its multiple antennas exceed a first threshold thatwould trigger ASDIV switching. The operations of block 1205 may beperformed according to the methods described herein. Aspects ofcommunication metrics (e.g., RSRPDelta, MPTL) and thresholds (e.g., 3dB) are described above. In certain examples, aspects of the operationsof block 1205 may be performed by a UE communications manager and/or aprocessor as described herein.

If the communication metrics do not exceed the first threshold at block1205, UE 115 ends method 1200 at block 1210. UE 115 may repeat method ona periodic basis, such as every 640 ms. If the communication metricsmeet or exceed the first threshold at block 1205, UE 115 compares thecommunication metrics to a second threshold that is greater than thefirst threshold at block 1215. In certain examples, aspects of theoperations of block 1215 may be performed by a UE communications managerand/or a processor as described herein.

If the communication metrics meet or exceed the second threshold atblock 1215, UE 115 begins the antenna switch, at block 1220, withoutwaiting for a silence window. Meeting or exceeding the second thresholdmay indicate that UE 115 may lose connection with base station 105 if UE115 waits for a silence window to execute the antenna switch. In certainexamples, aspects of the operations of block 1220 may be performed by aUE communications manager, a processor, a transceiver, a receiver,and/or a transmitter as described herein.

If the communication metrics do not meet or exceed the second thresholdat block 1215, UE 115 compares the amount of time until a silence windowoccurs to a time threshold and compares the duration or length of timeof the silence window (e.g., a silence duration) to the duration orlength of time of the antenna switch (e.g., a switch duration) at block1225. The operations of block 1225 may be performed according to themethods described herein. In certain examples, aspects of the operationsof block 1225 may be performed by a UE communications manager and/or aprocessor as described herein.

If the amount of time until the silence window meets or exceeds the timethreshold or the duration of the silence window is less than theduration of the antenna switch at block 1225, UE 115 begins the antennaswitch, at block 1220, without waiting for the silence window. If theamount of time until the silence window is less than the time thresholdand the duration of the silence window is greater than or equal to theduration of the antenna switch, UE 115 waits for the silence window toswitch antennas at block 1230. The operations of block 1230 may beperformed according to the methods described herein. In certainexamples, aspects of the operations of block 1230 may be performed by aUE communications manager and/or a processor as described herein.

At block 1235, UE 115 switches from the first antenna to the secondantenna during the silence window. In certain examples, aspects of theoperations of block 1235 may be performed by a UE communicationsmanager, a processor, a transceiver, a receiver, and/or a transmitter asdescribed herein.

Techniques described herein may be used for various wirelesscommunications systems such as code division multiple access (CDMA),time division multiple access (TDMA), frequency division multiple access(FDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and other systems.A CDMA system may implement a radio technology such as CDMA2000,Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000,IS-95, and IS-856 standards. IS-2000 Releases may be commonly referredto as CDMA2000 1×, 1×, etc. IS-856 (TIA-856) is commonly referred to asCDMA2000 1×EV-DO, High Rate Packet Data (HRPD), etc. UTRA includesWideband CDMA (WCDMA) and other variants of CDMA. A TDMA system mayimplement a radio technology such as Global System for MobileCommunications (GSM).

An OFDMA system may implement a radio technology such as Ultra MobileBroadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical andElectronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal MobileTelecommunications System (UMTS). LTE and LTE-A are releases of UMTSthat use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, NR, and GSM aredescribed in documents from the organization named “3rd GenerationPartnership Project” (3GPP). CDMA2000 and UMB are described in documentsfrom an organization named “3rd Generation Partnership Project 2”(3GPP2). The techniques described herein may be used for the systems andradio technologies mentioned above as well as other systems and radiotechnologies. While aspects of an LTE or an NR system may be describedfor purposes of example, and LTE or NR terminology may be used in muchof the description, the techniques described herein are applicablebeyond LTE or NR applications.

A macro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEs115 with service subscriptions with the network provider. A small cellmay be associated with a lower-powered base station 105, as comparedwith a macro cell, and a small cell may operate in the same or different(e.g., licensed, unlicensed, etc.) frequency bands as macro cells. Smallcells may include pico cells, femto cells, and micro cells according tovarious aspects. A pico cell, for example, may cover a small geographicarea and may allow unrestricted access by UEs 115 with servicesubscriptions with the network provider. A femto cell may also cover asmall geographic area (e.g., a home) and may provide restricted accessby UEs 115 having an association with the femto cell (e.g., UEs 115 in aclosed subscriber group (CSG), UEs 115 for users in the home, and thelike). An eNB for a macro cell may be referred to as a macro eNB. An eNBfor a small cell may be referred to as a small cell eNB, a pico eNB, afemto eNB, or a home eNB. An eNB may support one or multiple (e.g., two,three, four, and the like) cells, and may also support communicationsusing one or multiple component carriers.

The wireless communications system 100 or systems described herein maysupport synchronous or asynchronous operation. For synchronousoperation, the base stations 105 may have similar frame timing, andtransmissions from different base stations 105 may be approximatelyaligned in time. For asynchronous operation, the base stations 105 mayhave different frame timing, and transmissions from different basestations 105 may not be aligned in time. The techniques described hereinmay be used for either synchronous or asynchronous operations.

Information and signals described herein may be represented using any ofa variety of different technologies and techniques. For example, data,instructions, commands, information, signals, bits, symbols, and chipsthat may be referenced throughout the above description may berepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field-programmablegate array (FPGA) or other programmable logic device (PLD), discretegate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other aspects and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations.

Computer-readable media includes both non-transitory computer storagemedia and communication media including any medium that facilitatestransfer of a computer program from one place to another. Anon-transitory storage medium may be any available medium that can beaccessed by a general purpose or special purpose computer. By way ofexample, and not limitation, non-transitory computer-readable media maycomprise random-access memory (RAM), read-only memory (ROM),electrically erasable programmable read only memory (EEPROM), flashmemory, compact disk (CD) ROM or other optical disk storage, magneticdisk storage or other magnetic storage devices, or any othernon-transitory medium that can be used to carry or store desired programcode means in the form of instructions or data structures and that canbe accessed by a general-purpose or special-purpose computer, or ageneral-purpose or special-purpose processor. Also, any connection isproperly termed a computer-readable medium. For example, if the softwareis transmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, DSL, orwireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include CD, laser disc, optical disc, digital versatile disc (DVD),floppy disk and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

As used herein, including in the claims, “or” as used in a list of items(e.g., a list of items prefaced by a phrase such as “at least one of” or“one or more of”) indicates an inclusive list such that, for example, alist of at least one of A, B, or C means A or B or C or AB or AC or BCor ABC (i.e., A and B and C). Also, as used herein, the phrase “basedon” shall not be construed as a reference to a closed set of conditions.For example, an exemplary step that is described as “based on conditionA” may be based on both a condition A and a condition B withoutdeparting from the scope of the present disclosure. In other words, asused herein, the phrase “based on” shall be construed in the same manneras the phrase “based at least in part on.”

In the appended figures, similar components or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label, or othersubsequent reference label.

The description set forth herein, in connection with the appendeddrawings, describes example configurations and does not represent allthe examples that may be implemented or that are within the scope of theclaims. The term “exemplary” used herein means “serving as an example,instance, or illustration,” and not “preferred” or “advantageous overother examples.” The detailed description includes specific details forthe purpose of providing an understanding of the described techniques.These techniques, however, may be practiced without these specificdetails. In some instances, well-known structures and devices are shownin block diagram form in order to avoid obscuring the concepts of thedescribed aspects.

The description herein is provided to enable a person skilled in the artto make or use the disclosure. Various modifications to the disclosurewill be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other variations withoutdeparting from the scope of the disclosure. Thus, the disclosure is notlimited to the aspects and designs described herein, but is to beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method for wireless communication in amulti-antenna user equipment (UE), comprising: communicating with a basestation using a first antenna; determining to switch from the firstantenna to a second antenna for communicating with the base station;determining a silence window in which communication with the basestation is suspended; scheduling the switch from the first antenna tothe second antenna to occur during the silence window; and switchingfrom the first antenna to the second antenna during the silence window.2. The method of claim 1, further comprising assessing communicationmetrics to determine whether to switch from the first antenna to thesecond antenna.
 3. The method of claim 2, wherein the communicationmetrics include a combination of downlink communication metrics anduplink communication metrics.
 4. The method of claim 3, wherein thedownlink communication metrics are associated with the first antenna andthe second antenna and the uplink communication metrics are associatedwith the first antenna.
 5. The method of claim 3, wherein the downlinkcommunication metrics and the uplink communication metrics correspond tocommunication metrics filtered over time.
 6. The method of claim 3,wherein the downlink communication metrics correspond to received signalmeasurements and the uplink communication metrics correspond totransmission power metrics.
 7. The method of claim 2, furthercomprising: comparing the communication metrics to a first threshold todetermine whether to switch from the first antenna to the secondantenna; and comparing the communication metrics to a second thresholdto determine whether to wait for the silence window to perform theswitch or to perform the switch before the silence window.
 8. The methodof claim 7, wherein each of the first threshold and the second thresholdinclude one or more downlink thresholds and one or more uplinkthresholds.
 9. The method of claim 1, further comprising determiningwhether the first antenna, the second antenna, or both are shared amonga first radio access technology (RAT) and a second RAT.
 10. The methodof claim 9, further comprising: communicating via the first antennausing the first RAT and the second RAT; and communicating via the secondantenna using the first RAT and the second RAT.
 11. The method of claim10, wherein communications using the first RAT and the second RAT aresuspended during the silence window.
 12. The method of claim 1, whereinthe silence window corresponds to a measurement gap.
 13. The method ofclaim 1, wherein the first antenna, the second antenna, or both areshared among a first radio access technology (RAT) and a second RAT, andwherein the silence window corresponds to a measurement gap for both thefirst RAT and the second RAT.
 14. The method of claim 1, wherein thesilence window corresponds to a connected mode discontinuous reception(CDRX) off duration.
 15. The method of claim 1, wherein the firstantenna, the second antenna, or both are shared among a first radioaccess technology (RAT) and a second RAT, and wherein the silence windowcorresponds to a window in which a connected mode discontinuousreception (CDRX) off duration of the first RAT overlaps in time with aCDRX off duration of the second RAT.
 16. The method of claim 1, furthercomprising determining that a current active service at the UE is avoice service, the voice service having a silence interval descriptorpacket, wherein the silence window corresponds to a voice silenceduration associated with the silence interval descriptor packet.
 17. Themethod of claim 1, further comprising: determining a switch durationcorresponding to a length of time to switch from the first antenna tothe second antenna for communicating with the base station; determininga silence duration corresponding to a length of time of the silencewindow; and comparing the switch duration to the silence duration,wherein the switch from the first antenna to the second antenna isscheduled during the silence window in response to the silence durationbeing equal to or greater than the switch duration.
 18. The method ofclaim 1, further comprising: communicating with the base station usingthe first antenna and a third antenna in an uplinkmultiple-input-multiple-output (MIMO) configuration; determining toswitch from the first and third antennas to the second antenna and afourth antenna for uplink communications with the base station;scheduling the switch from the first and third antennas to the secondand fourth antennas to occur during the silence window; and switchingfrom the first and third antennas to the second and fourth antennasduring the silence window.
 19. The method of claim 18, whereindetermining to switch from the first antenna is independent fromdetermining to switch from the third antenna.
 20. A user equipment (UE)for wireless communication, comprising: a first antenna; a secondantenna; a processor; memory coupled to the processor; and instructionsstored in the memory and operable, when executed by the processor, tocause the UE to: communicate with a base station using the firstantenna; determine to switch from the first antenna to the secondantenna for communicating with the base station; determine a silencewindow in which communication with the base station is suspended;schedule the switch from the first antenna to the second antenna tooccur during the silence window; and switch from the first antenna tothe second antenna during the silence window.